The present invention relates generally to methods for making slot closure wedges for magnetic stator cores at a station where coils and wedges are axially injected into axial slots of such cores; and more particularly where such wedges are formed into a desired shape by rollers and fed by pinch roller action to a wedge cutting mechanism adjacent to a wedge magazine that is disposed generally collinearly with axially extending coil injection tools.
Numerous patents in the art illustrate methods and apparatus wherein wedges are made in a wedge maker, placed in a wedge magazine disposed generally collinear with axially extending coil injection blades or tools, and wherein the wedges subsequently are inserted axially into stator core slots along the trailing ends of stator coils that are also being axially inserted into such slots. The wedges then lie between side turn portions of the slots and the stator bore, and sometimes lie adjacent the bore and effectively "close" such slots. Morr U.S. Pat. No. 3,872,568 which issued Mar. 25, 1975 is one patent which illustrates an arrangement as just described, and further general background information is supplied at lines 1-50 of column 1 of this patent, the entire disclosure of which is incorporated herein by reference.
Another patent (the entire disclosure of which is also incorporated herein by reference) which pertains to this art is Eminger U.S. Pat. No. 3,447,225 which issued June 3, 1969. This particular patent recognizes a problem that has become known in the art as the "wire over wedge" problem. This particular problem has continued to trouble the industry, and the inventions described in the present application are intended, among other things, to solve this problem.
Still other patents that illustrate apparatus of the type to which the present invention may be applied are Hill U.S. Pat. No. 3,324,536 of June 13, 1967; Lauer et al U.S. Pat. No. 3,829,953 of Aug. 20, 1974; Arnold et al U.S. Pat. No. 3,579,818 of May 25, 1971; and Smith et al U.S. Pat. No. 3,831,255 of Aug. 27, 1974; the entire disclosures of all of which are incorporated herein by reference.
Apparatus for practicing my invention in one preferred form differs from the prior art mentioned hereinabove at least in that wedge material is selectively fed by a pinch wheel arrangement that serves both as a feeding mechanism and as a means for forming wedge material into a predetermined shape, and in that the wedge material is substantially immediately thereafter severed into individual wedges and then inserted into a wedge magazine. Shortly thereafter, e.g., within one machine injection cycle, the wedges are axially placed in core slots.
Peters U.S. Pat. No. 3,805,357 of Apr. 23, 1974 illustrates a pinch wheel feed arrangement for stator core wedge material which is formed into wedges by a wedge forming die spaced from the pinch wheel feed mechanism. Peters U.S. Pat. No. 3,909,902 of Oct. 7, 1975 also shows a pinch wheel feed mechanism for insulating material (best seen in FIG. 5 of the patent), but in the context of a non-analogous ground insulation cell inserting machine rather than a wedge maker; Ott U.S. Pat. No. 3,758,937 of Sept. 18, 1973 shows a pinch wheel fed wedge inserter for the non-analogous armature art.
Machine Products Corporation of Dayton, Ohio has sold, more than a year prior to this application, a pinch wheel fed stator wedge maker which forms wedges which ultimately are placed in slots of cores that have previously had windings placed therein; and Lakes Engineering of Bluffton, Indiana has, more than a year prior to the filing date of this application, sold what is known as a "hot former mylar wedge maker". However, the two machines just mentioned are sold for making wedges per se, and the present invention is directed to the solution of problems encountered in apparatus of the type wherein wedge making and wedge insertion is accomplished with the same equipment that is utilized for stator coil "injection" (or "placing" as it is sometimes called in the art).
In the prior art equipment of the type where wedge making and insertion mechanisms are combined with coil injection mechanisms; the wedge material most typically is advanced with a "hitch" feed as shown for example in FIG. 2 of the above referenced U.S. Pat. No. 3,579,818. Moreover, in equipment of this combined function type, the wedges themselves are formed by dies which include a die movable transversely to the direction in which the wedge material is being fed. Very often, such movable die also places the wedge in the wedge magazine. The wedges so made are placed in a magazine and then, as winding sideturn portions of coils are moved from the tooling of the combined function equipment and axially into axially extending slots of a stator core, the wedges are axially advanced immediately behind the winding side turn portions. It is intended, with all such equipment, that all of the side turn portions being inserted in a given slot be positioned "under" the following wedge being placed in the same slot. In other words, none of such winding turn portions (or segments thereof) should be "over" the wedge and thus lie between the wedge and the bore of the stator.
However, experience has shown that the wire over wedge problem has persisted, despite efforts to overcome the problem. Moreover, the wedge material feeding and forming apparatus of the prior art machines has been relatively complex and thus relatively difficult to make and maintain, and especially so when provision must be made for "skipping" predetermined wedges.
It thus should be understood that it would be desirable to provide new and improved methods utilizing combined function apparatus for wedge making and inserting and coil injecting that overcome the above-mentioned problems.
Accordingly, it is an object of the present invention to provide new and improved methods for making and inserting stator core wedges, and for inserting windings into axially extending slots of a stator core that open into an axially extending bore.
A more specific object of the present invention is to provide methods whereby wedges are precisely dimensioned, and substantially immediately placed in a wedge storage magazine and placed in slots of a core shortly after wedge manufacture, whereby wire over wedge problems are alleviated.
Still another object of the invention is to provide new and improved methods that satisfy the objects stated hereinabove, and yet wherein the manufacture of wedges may be performed or omitted in preselected patterns.